In order to provide turbines a more efficient gas turbine there may be a need to reduce high levels of fluid dynamic during injection of a gas/fuel mixture into a combustion system of a turbine. While running on liquid fuel, the combustion system produces high levels of combustion dynamics, such as pressure changes of a fuel, changes in the flow direction of the fuel air mixture and flame dynamics, which may cause over a period of time fretting or component failure.
In conventional systems this problem has been solved in two ways. Firstly, a series of small holes may be provided in a flame tube of the combustion system to give the best compromise between cooling the flame tube wall and providing an air film over the components in order to protect the same from fretting. This barrier of cooling air may also provide acoustic damping. Secondly, a fuel to air ratio between the main burner and the pilot burner may be varied in order to reduce the dynamics.
EP 0722065 A2 discloses a fuel injector arrangement for gas- or liquid-fuels turbines. The arrangement comprises means for producing at least one air stream for mixing with a supply of fuel but wherein the supply of fuel is initially injected into at least one zone adjacent an air stream but shielded therefrom. Thereby, fuel rich pockets of fluid are formed in these zones. The pockets ensure flame stability at least at lower power settings. The zone is defined by a wall of a swirler. The fuel is injected through nozzles and additional nozzles for a supplementary supply of fuel may be provided in a block.
EP 0957311 A2 discloses a gas-turbine engine combustor. A lean burn combustor of a gas-turbine engine has a radial inflow pre-mixing, pre-swirling burner with a central burner face which forms an upstream wall of a pre-chamber of the combustor. A circular recess is faulted in the burner face. The recess comprises at least one pilot fuel injector for introducing pilot fuel tangentially into the recess.
EP 1 890 083 A1 discloses a fuel injector for a gas-turbine engine. A ring-shaped fuel injector comprises an inner diameter and an outer diameter. Furthermore, the ring-shaped fuel injector comprises a fuel groove arranged in a face side of the ring and at least one fuel injection opening is arranged on the ring and is connected to the fuel groove.
EP 1 867 925 A1 discloses a burner, in particular a gas turbine burner. A swirler of the burner comprises at least one air inlet opening, at least one air outlet opening that is positioned downstream to the air inlet opening and at least one swirler air passage extended from the at least one air inlet opening to the at least one air outlet opening which is delimited by swirler air passage walls. At least the downstream section of one air passage wall is thereby conjugated.
U.S. Pat. No. 5,941,075 discloses a fuel injection system with improved air/fuel homogenization. The system is adapted for injecting air and fuel into a combustion chamber of a turbojet engine. A housing is located rearwardly of a first radial swirler and forming a pre-mixing chamber bound by a conversion/diversion wall forming a venturi with a throat. The housing having a plurality of second air passages forming a second radial swirler to direct air into the pre-mixing chamber forward of the venturi throat in a second plane generally perpendicular to the axis A. Thereby, the second passages and the third passages alternating in a circumferential direction around the housing.